Comment on Mineral Diversity on Europa: Exploration of Phases Formed in the MgSO4-H2SO4-H2O Ternary

The structure of a new polymorph of MgSO4 center dot 6H(2)O, a potentially important mineral on the surface of Europa, one of Jupiter's icy moons, was reported by Maynard-Casely et al. [Maynard-Casely, H. E.; Brand, H. E.; Wilson, S. A.; Wallwork, K. S. Mineral Diversity on Europa: Exploration of Phases Formed in the MgSO4-H2SO4-H2O Ternary. ACS Earth Space Chem. 2021, 5 (7), 1716-1725. DOI: 10.1021/acsearthspacechem.1c00073]. The reported structure is unambiguously incorrect because the stoichiometry is wrong; the formula unit contains only half of the SO42- oxyanions required. We highlight where this error could have been detected at various stages of the analysis, writeup, and submission process and make recommendations to avoid repetition of the mistake.

Automated summary

The structure of a new polymorph of MgSO4·6H2O, a potentially important mineral on Europa, was reported but found to have a stoichiometric error where only half of the required anions were present. The study highlights the stages where this error could have been detected and provides recommendations to prevent its repetition.